Chronologically, Marshall is the third member of the gang to meet Tracy. After stealing Darren's van in an act of Aldrin Justice, Tracy picks up Marshall from the side of the road after the bus he was riding broke down. Marshall is at first freaked out that Tracy knows so much about him, believing her to be psychic. Tracy then tells Marshall that she met Lily on the train, and thats how she knows about him and Marvin. They see each other again two days later at Barney and Robin's wedding, but don't actually interact.